The present invention relates to a Bifidobacterium bifidum proliferation promoting composition. More particularly, the present invention pertains to a Bifidobacterium bifidum proliferation promoting composition comprising a xylooligosaccharide which contains xylobiose as its principal component.
Among a large number of known bacteria that constitute the enterobacterial flora, Bifidobacterium bifidum is one of the bacteria which are regarded as useful to man. Numerous reports have been made on the physiological significance of Bifidobacterium bifidum. It is widely known that Bifidobacterium bifidum has the following favorable activities: e.g., the activity of suppressing putrefaction caused by entero putrefactive bacteria; the activity of preventing production of toxic amines; the activity of suppressing the proliferation of pathogenic bacteria by the production of organic acids such as lactic acid, acetic acid, etc.; and the activity of promoting digestion and absorption of nutrients.
It is known that the maintenance of a balance between the various bacteria that constitute the enterobacterial flora is closely related to man's health and, when pathogenic bacteria which are usually in the minority in the intestines become predominant, the symptoms of a disease develop. A typical example is diarrhea which occurs as a result of the disappearance of Bifidobacterium bifidum or the action of Escherichia coli or Staphylococcus. Bifidobacterium bifidum is also closely related to infant health. More specifically, Bifidobacterium bifidum is predominant in the enterobacterial flora of healthy infants, but in the case of an infant suffering from exudative diathesis, certain kinds of enterococcus which suppress proliferation of Bifidobacterium bifidum are at all times predominant in the enterobacterial flora. It is known that the feces of a dysenteric infant have a markedly lowered Bifidobacterium bifidum content and the relative proportions of the various bacteria in the enterobacterial flora is considerably out of balance.
On the basis of these various known facts, a typical well-balanced enterobacterial flora is now considered to be such that Bifidobacterium bifidum, which has excellent staying and proliferation potencies in the intestines, is most predominant at all times.
In view of the useful activities of Bifidobacterium bifidum, various kinds of Bifidobacterium bifidum-containing preparations and dairy products have recently been developed for the purpose of increasing the amount of Bifidobacterium bifidum in the intestines.
However, if Bifidobacterium bifidum is taken orally, it will not generally stay in the intestines, and in many cases, as soon as the intake of Bifidobacterium bifidum is stopped, the enterobacterial flora returns to the previous state.
It is considered that the most essential factor for the proliferation of Bifidobacterium bifidum in the intestines is saccharides, and the effectiveness of lactulose for this purpose was in the past pointed out.
Lactulose is a sugar which is obtained by replacing the glucose portion of lactose with fructose and which can be slightly assimilated. Therefore, when lactulose is taken orally, most of it reaches the large intestine without being absorbed into the body and is assimilated by enterobacteria. However, lactulose is not necessarily assimilated preferentially by Bifidobacterium bifidum as it is also assimilated by other enterobacteria such as Escherichia coli, Clostridium, etc. It is therefore difficult to selectively encourage Bifidobacterium bifidum alone to proliferate.
Recently, studies have been vigorously under taken to develop a method of promoting the proliferation of Bifidobacterium bifidum by means of saccharides, and it has been found that fructooligosaccharide, isomaltose, etc. are effective in promoting the proliferation of Bifidobacterium bifidum. However, in the case of isomaltulose, although its Bifidobacterium bifidum proliferation activity is found in vitro, the activity disappears in vivo. Therefore, isomaltose is less effective as a Bifidobacterium bifidum proliferating saccharide.
Fructooligosaccharide is a sugar which consists of sucrose and 1 to 4 molecules of fructose which are connected thereto; it is selectively assimilated by Bifidobacterium bifidum and neither digested nor absorbed by a living body. Accordingly, it has been confirmed that fructooligosaccharide can be used to promote selectively the proliferation of Bifidobacterium bifidum in the intestines. However, fructooligosaccharide is prepared by transferring fructose to sucrose by means of fructose transferase and the stability of the thus prepared fructooligosaccharide is not necessarily satisfactory. In particular, when it is stored for a long time in a liquid state, the sugar changes into glucose, fructose and sucrose and its Bifidobacterium bifidum proliferation activity lowers as it changes.